This invention relates generally to improvements in and relating to pushbutton-operated controls adapted for on-off and functional control of various appliances, and more specifically for those usable in and on automotive vehicles. Thus, the present invention may be applied to the control of automotive door locks, on off control of an engine, trunk lid lock, openable ceiling panel on-off control, on off control of interior light(s), driver's seat door lock and the like.
As a representative example, although not limited only thereto, the following description will be directed mainly to an automotive door lock and unlock system.
It has already been proposed to control the automotive door locks by means of pushbuttons in place of conventional engine key and the like. In this case, these locks are designed into solenoid-operated electric locks which are functionally controlled by electronic circuits.
This kind of electronic control system comprises a memory which is adapted for memorizing a specifically selected permanent code signal by sequential manipulation of push-buttons constituting a code presetter. There is a comparator which is adapted for making comparison of an arbitrary code signal introduced by similar manipulation of the presetter pushbuttons, with the memorized permanent code signal. If there is a coincidence between both, the electric lock(s) are unlocked. There may occur, however, that an unauthorized person is knowledgeable of the already specified permanent code signal, leading thus to a theft unlocking.
For effectively solving such kind of theft unlocking, it has already been proposed to provide an arbitrary code signal memory in such a way that the operator can modify or completely change the once preset control code signal. With such memory system as mentioned above, a door lock release can be performed by later and intentional introduction of either the permanent or the arbitrary code signal by sequential manipulation of the presetter pushbutton switches. With adoption of such memory system, however, the selectability of either code signal will be reduced so far that the possibility of confusion among prevailing automotive vehicles and a theft unlocking accident might occur.